The goal of this observational study is to learn about vaccine immunity in patients with B-cell malignancies treated by chimeric antigen receptor T-cell therapies (CAR-T). The main questions it aims to answer are: * Do CAR-T cell therapy recipients lose vaccine protection against common vaccine-preventable pathogens * Are current re-vaccination recommendations sufficient in restoring vaccine-protection * Is this restored vaccine-protection after CAR-T cell therapy lost faster than usual * Do clinical or immunological factors predict vaccine response after CAR-T cell therapy